lib: Simplify the list of mappings
lib: Simplify the list of mappings

There's no reason to hide the list of mappings behind a structure. We
can instead store the list directly in VhostUserHandler structure.

Signed-off-by: Sebastien Boeuf <90b401417360b1924ef3f520ddee932686110f85@intel.com>

rust-vmm/vhost